Revealing mistake: When Phil drives the truck off the cliff, you can see right through the grill of the truck (meaning there is no radiator or engine), and the transmission is also missing, as you can see when the truck is falling upside down. Without an engine or transmission it would be hard to drive off a cliff.
Revealing mistake: When Phil escapes the police with his drunk friends in the car, their stunt doubles' different faces are visible as they start driving on the tracks.
Chosen answer: As you stated, it's never addressed as to whether or not he attempted to leave town. Phil lived through many more days than is shown in the film, so it's possible he left at some point, though there's little reason for him to do so because he wouldn't get far, and, when he wakes up the next morning, he'll be right back in the town.
raywest ★